Reply to ‘Comments on: Season and phosphorus age effects on the relationship between maize yield and phosphorus soil test on a highly weathered soil’

Farina, M. P. W.; Channon, P.

doi:10.1080/02571862.1987.10634953

Cited by 7 publications

(7 citation statements)

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“…A salient feature of the relationship between P soil test and relative yield is the indication that P requirement for optimum dry matter production remained the same in both seasons, despite meaningful differences in seasonal dry matter production. Similar observations have been reported by Farina & Channon (1987), in their studies on maize. These findings refute the widely held view that P requirement is reduced under conditions of moisture stress.…”

Section: Discussionsupporting

confidence: 87%

Lime and phosphorus effects on the dry matter production oferagrostis curvulaon dystrophic clay soils

Miles

Villiers

1989

Journal of the Grassland Society of Southern Africa

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Section: Discussionsupporting

confidence: 87%

Lime and phosphorus effects on the dry matter production oferagrostis curvulaon dystrophic clay soils

Miles

Villiers

1989

Journal of the Grassland Society of Southern Africa

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“…The level of K in the soil which is needed to achieve this maximum maize yield was called by Bray (1944) the "soil K requirement". Farina and Channon (1987;1991) confirmed the validity of the Mitscherlich-Bray percentage sufficiency concept in phosphorus and soil acidity studies in Kwa-Zulu-Natal. Farina et al (1992) concluded that on kaolinitic clay soils exchangeable K provides an excellent index for K fertilizer application rates for maize and that K fertilization for maximum yield appeared to be thoroughly justified.…”

Section: Threshold Values and Sufficiency Levels For Potassium In Maimentioning

confidence: 52%

Threshold values and sufficiency levels for potassium in maize producing sandy soils of South Africa

Biljon

Fouche

Botha³

2008

South African Journal of Plant and Soil

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South African maize farmers apply only two thirds of the potassium (K) which is annually removed in the grain, causing a deficit of more than 13 000 tons K per season. It is expected that these maize fields will gradually become depleted and more K will be required to maintain or improve yields. Research goals were set for sandy soils in the main maize producing areas of South Africa to determine the lower & upper threshold values and sufficiency levels for soil K, the K status of these soils and to evaluate the sufficiency level concept for K at the various localities in the Free State Province. Field experiments were conducted at nine localities during four consecutive seasons. The experimental data included the soil K extracted with NH 4 OAc and the relative maize yields (RY) of the treatments, +K which received macro, secondary and micro nutrients and 0K which received the same nutrients but K was omitted. The results indicated a lower threshold value of 125 mg K kg -1 below which maize is expected to respond positively and an upper threshold value of 190 mg K kg -1 above which maize is expected not respond to additional K. The extractable K from 25 000 sandy soil samples received from maize farmers indicated that approximately 50% of these samples contained less K than the lower threshold value, approximately 30% was between the lower and upper threshold values and the remaining 20% was above the upper threshold value. The sufficiency levels obtained with the Mitscherlich model at 98% RY, ranged from 109-340 mg K kg -1 . The difference between the sufficiency values and the extractable soil K at any of these localities, gives an unbiased measurement of the K fertilizer to be recommended.

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“…If interpreted with circumspection, tissue tests can provide a valuable a posteriori decision-making aid, but the prediction of fertilizer requirement is soil dependent and research directed towards the acquisition of soil test calibration data must remain an important priority in this country. The validity of the Mitscherlich-Bray percentage sufficiency concept, previously confirmed locally in P and soil acidity studies (Farina & Channon, 1987;1991), gives field experimentation considerable short-term relevance if achievable long-term yield maxima can be reliably estimated. Local progress in the field of crop modelling (De Jager, 1987;J.B.…”

Section: Relationship Between Relative Yield and Plant K Indicesmentioning

confidence: 93%

Soil and plant potassium optima for maize on a kaolinitic clay soil

Farina

Channon

Thibaud

et al. 1992

South African Journal of Plant and Soil

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In South Africa, there is an extreme paucity of information relating maize (Zea mays L.) yields to soil and plant K levels and most K fertilizer recommendations are highly subjective. Controversy also surrounds the practice of relating K fertilizer recommendations to estimates of yield potential. The work reported here was conducted to address these shortcomings. The yield and plant compositional response of maize to a range of soil K levels was studied for eight seasons on a Metz clay soil (clayey, kaolinitic, thermic Plinthustalf). Relative yields were related to exchangeable soil K and the leaf parameters: K content, (Ca + Mg)/K and K ORIS index. Although grain yield maxima varied from 5.85 to 10.80 Mg ha-1 , 91 % of the relative yield variability was explainable in terms of exchangeable soil K. Leaf-based indices were also closely related to relative yield, but were sensi!ive to variatio~s in top~oil moisture status prior .to sampling ~nd ~ere ~~t considered dia~nosti cally superior to the K sOil test. It IS concluded that the optimum K level In thiS SOil IS c. 0.32 cmol L-, that there is no justification for relating K requirement to estimates of yield potential and that leaf diagnostic criteria should be interpreted with circumspection.In Suid Afrika bestaan daar 'n groot gebrek aan inligting betreffende die verband tussen mielie (Zea mays L.) opbrengste en grond en plant K peile en die meeste K bemestings -aanbevelings is dan ook hoogs subjektief. Daar bestaan ook verwarring rondom die koppeling van K bemestings -aanbevelings aan skattings van opbrengs potensiaal. Hierdie werk is onderneem ten einde die tekortkomings aan te spreek. Die opbrengs en plant samestelling respons van mielies onderworpe aan 'n reeks van grond K peile is bestudeer oor 'n tydperk van agt seisoene op 'n Metz kleigrond (kleierige, kaolinitiese, termiese Plinthustalf). Relatiewe opbrengste is in verband gebring met uitruilbare grond K en die blaar parameters, K-inhoud, (Ca + Mg)/K en ORIS indeks. Alhoewel die maksimum graanopbrongs gevarieer het van 5.85 tot 10.80 Mg ha-1 , was 91 % van die relatiewe opbrengs variansie verklaarbaar in terme van uitruilbare grond K. Blaar-gebaseerde indekse was ook nou verwant aan relatiewe opbrengs, maar was sensitief tot veranderings in bogrond vog status voor monsterneeming en was nie as diagnosties beter as grond K toets beskou nie. Die gevolgtrekking van hierdie studie is dat die optimum grond K peil in hierdie grond ongeveer 0.32 cmol L-1 is en dat daar geen regverdiging bestaan om K benodighede te koppel aan skattings van opbrengs potensiaal nie. Blaar diagnostiese norme moet met omsigtigheid ge"interpreteerword.

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Reply to ‘Comments on: Season and phosphorus age effects on the relationship between maize yield and phosphorus soil test on a highly weathered soil’

Cited by 7 publications

References 0 publications

Lime and phosphorus effects on the dry matter production oferagrostis curvulaon dystrophic clay soils

Lime and phosphorus effects on the dry matter production oferagrostis curvulaon dystrophic clay soils

Threshold values and sufficiency levels for potassium in maize producing sandy soils of South Africa

Soil and plant potassium optima for maize on a kaolinitic clay soil

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